Thanks Varun but this is not what I wanted.
We were upgrading our old UAT Server to a New UAT Server. The Old server didn't had a hostname and thus the users were using it with the servername url.
Even though qlikview officially doesn't support changing the files, I was able to achieve it by changing the Index.htm file. Just change the old server index.htm & add the below line after the </head>.
<META http-equiv="refresh" content="0;URL=http://newserver/qlikview/index.htm">